The present invention relates to an accessor mechanism included in a recording medium library for conveying a cartridge between a rack or preselected position and a medium driver. More particularly, the present invention relates to a picker mechanism for picking up a cartridge located at the preselected position, conveying the cartridge to another preselected position, and then releasing the cartridge.
A recording medium library stores a number of optical disk cartridges, magnetic tape cartridges or similar data recording media and loads a drive unit thereof with designated one of the cartridges for a recording or reproducing purpose. A tape library, for example, includes an entry/exit device having cells arranged in the vertical and horizontal directions and an accessor device for picking up a magnetic tape cartridge stored in any one of the cells. When the operator of the library inserts a cartridge into the entry/exit device, a picker mechanism mounted on the accessor device senses the cartridge, picks up the cartridge, and then moves the cartridge to a preselected position.
In a disk library, an accessor device accesses one of optical disk cartridges stacked on a rack, picks up the cartridge, conveys the cartridge to a disk driver, loads the disk driver with the cartridge, and then returns the cartridge to the rack after recording or reproducing data in or out of the cartridge.
One of conventional picker mechanisms for the above accessor device includes a pair of fingers to which a pair of link members are pivotally mounted. A single drive motor selectively causes two cams to rotate. When the motor causes one of the cams to rotate, the cam causes the fingers to open and close via the link members. When the motor causes other cam to rotate, the cam causes the fingers to move back and forth via the link members. This kind of picker mechanism is disclosed in, e.g., Japanese Patent Laid-Open Publication No. 1-237953. The picker mechanism, however, must open and close the fingers or move them back and forth at accurate timing and therefore require the cams to have high accuracy and to be accurately mounted to the drive motor, resulting in an increase in cost.
Another conventional picker mechanism includes a pair of fingers each carrying a roller on its free end and caused to open and close by a drive motor, as taught in Japanese Patent Laid-Open Publication No. 6-36435 by way of example. The drive motor causes the rollers to close toward each other and thereby causes the fingers to grip a cartridge. Subsequently, another motor causes the rollers to rotate in order to pull in the cartridge. This picker mechanism opens and closes the fingers without reducing the rotation speed of the drive motor and therefore at high speed. However, the force of the fingers gripping a cartridge is weak and apt to cause the cartridge to slip out of the fingers.
Still another conventional picker mechanism includes a speed reduction mechanism intervening between a drive motor and a pair of fingers for guaranteeing a great torque, as proposed in Japanese Patent Laid-Open Publication No. 8-127402. The picker mechanism causes the fingers to open and close with such a torque. While this picker mechanism allows the fingers to firmly grip a cartridge, the speed reduction mechanism increases the number of parts and slows down the opening and closing actions of the fingers.
Technologies relating to the present invention are also disclosed i n, e.g., Japanese Patent Laid-Open Publication Nos. 61-255557 and 3-241562.
It is therefore an object of the present invention to provide a simple, low cost picker mechanism for a recording medium library capable of causing fingers thereof to open and close instantaneously and grip a cartridge with a sufficient force.
A picker mechanism for automatically taking a cartridge storing a recording medium into and out of a preselected position of a recording medium library of the present invention includes a pair of fingers openable away from each other for gripping the cartridge therebetween. Biasing members constantly bias the fingers toward a closed position. An opening member forces the fingers open against the action of the biasing members when moved forward to an advanced position. A solenoid causes the opening member to move between a retracted position and the advanced position.